The staging of a theatrical production typically requires the creation of a variety of sets to be utilized during the production. As the play progresses and the scenes change, sets must be positioned on and removed from the stage. Depending on the production, the number and size of the sets may be substantial, with a great number of set changes being required.
Typically, the changing of the sets is manual labor performed by a crew of stagehands, utilizing a complex series of lines and pulleys. Banks of lifting lines, normally of wire rope, are located to a side of the stage, out of the sight of the audience, with the lines running vertically to a point high above the stage and then horizontally to other banks of pulleys located above the stage. During preparation for the production, the lines are run to the appropriate over-stage pulleys such that all of the scenery utilized during a production can be positioned on the stage floor as appropriate. The lines are connected to the scenery flats, which are then raised high over the stage, out of view of the audience, to be lowered onto the stage and into the view of the audience as required during the production. To insure that the scenery not in use at a particular time is fully out of view, the over-stage pulleys must be located at an elevation at least twice the proscenium height.
Because of the variable size and often great weight of the sets, the lift line groups for each set are provided with a counterbalance system to offset the set load and to make it easier for the stagehands to raise and lower the sets. The control and operating line for the counterweight is provided with a clamping system which allows the position of the lift lines and the set to which they are affixed to be maintained in position to avoid inadvertent movement.
There have been attempts to replace the manual system outlined above with mechanized and automated set lift systems. Generally, such systems are intended to replace the manual system, and thus require the complete removal of the manual system, with an attendant significant cost. In addition, because the set lift system must allow for locating sets of varying sizes anywhere on the stage, the cost of providing mechanized controllers able to accommodate such variation is substantial. Thus, while the staging of a given production may utilize only a small portion of the available lift capacity, the lift system installed must nevertheless have the ability to handle sets located anywhere across the entire stage area. Much of the installed capacity is accordingly not normally utilized.
It is accordingly a purpose of the present invention to provide a mechanized stage scenery lift apparatus which may be utilized and installed in connection with presently-installed manually-operated scenery lift systems.
Yet another purpose of the present invention is to provide a mechanized scenery lift control system which may be retrofit into existing manual systems without preventing use of the manual system.
Still another purpose of the present invention is to provide such a system which provides for effective and efficient use of the motor drive elements such that it is not necessary that a substantial portion of the motive power available remains unutilized.